1 The feeding problem is quite complicated. It is necessary to analyze the specific problem and see where the extruder is blocked.
2 Fixed first layer problems can be solved with double-sided tape.
3 Refueling is to completely abandon the old materials, do not ask yourself for trouble.
4 Clean the nozzles, use new steel balls, nozzles with sewing needles, or the E string of the guitar is a good alternative.
Other problems are still there, such as the drawing phenomenon of the feed, to continue research, adjust a good z_offset.